Gold has been used therapeutically since ancient times. Orally administrable gold based products are known in traditional and alternative medicine. Further, gold based products obtained through various chemical reduction processes, ingestible and injectable, are also available for treatment of humans and animals. Gold salts obtained through chemical reduction are noticed to cause side effects due to toxicity thereby limiting its therapeutic application. Despite chemical purification, impurities are found on the surface of the gold particles, which causes various side effects upon administration in humans and animals. The toxicity of the gold based product causes side effects like nausea, vomiting, diarrhoea, dermatitis, haematological disorder. The main reason attributed to the toxicity is the change in oxidation state after administration and the carrier molecule. Orally administrable therapeutic gold products obtained through chemical reduction, for instance Auranofin or Ridaura, are noted to be less therapeutically effective than injectable gold salts.
With the advent of nano gold particles obtained through chemical reduction, e.g., by water arcing, electrochemical process etc., the therapeutic applicability of gold has improved. However, colloidal gold, obtained through chemical reduction processes results in stable and partially stable gold colloids or gold nano suspensions and are found to be less effective when orally administered. Nano gold products obtained through electrochemical processing have been found to have cleaner particle surfaces thereby increasing its efficacy in vivo and the particle size range from 8 nm to 100 nm as described in PCT/US2010/041427.
Gold based products known to have anti inflammatory properties and bacteriostatic effect are used in the treatment of rheumatoid arthritis, tuberculosis, cancer, asthma, HIV, Malaria etc. However, the toxicity and in vivo oxidation factor has caused its use in humans and animals to be restricted
Further, gold nano particles, more robust and stable, are one of the most preferred nano materials in technological applications especially biomedical applications such as bio imaging.
The production of nano gold through various methods is known by those of skill in the art. Except, however, for process of production of ‘swarna bhasma’ there is no other known existent process to obtain nano gold through bio synthesis. The swarna bhasma, comprising of gold containing globular particles having an average size of 56 nm-57 nm, has been an integral part of traditional medicine in India. The traditional method comprises the steps of (1) purification with the aid of sesame oil (Sesamum Indicum Linn.), butter milk, cow's urine, sour gruel processed from Oryza Sativa, and extract of Dolichos biflorous Linn (2) special purification with the aid of hematite and rock salt and heating process (3) process of incineration by addition of mercury and sulphur in required proportion. The resultant product is a brownish red powder ‘swarna bhasma’. (Brown C L et al, Gold Bulletin 2007).
The production and use of ‘swarna bhasma’ is further discussed in PCT/IN2008/000816, where the ‘swarna bhasma’ produced through traditional method is claimed in a method to perpetuate stemness in stem cell therapy. However, the process or the product discussed in that application is not similar to the present invention.
There exists the need for nano gold, stable and more robust, with higher mobility, adequate therapeutically effective particle size, and low toxicity to expand the applicability of gold metal.